Apparatus for applying plastic coatings to flexible strips and the like



June 4, 1546.

H. A. cooK, JR

APPARATUS FOR-APPLYING PLASTIC COATINGS TO FLEXIBLE STRIPS THE LIKE Original Filed June 16, 1943 s Shets-Sheet 1 A o vacuum PUMP '2 s'rgnm 1.11 12 1 5 56 A '6 9 1s 2 v 1 36 's'rizm LINE,

ATTORNEYS.

June 4,;1946, AQCQQKJR 2,401,551

- APPARATUS FOR APPLYING PLASTIC COATINGS TO FLEXIBLE STRIPS THE LIKE Original Filed June 16, 1943 3 Sheets-Sheet 2 51 as 1 24 I fl25 I I V .mmvrdnv ATTORNEYS.

Patented June 4; 1946 I I APPARATUS FOR APPLYHVG PLASTIC COAT- "INGS TO FLEXIBLE STRIPS AND THE LIKE Herbert Alton Cook, Jr., Auburn, N. Y., assignor to Auburn Button Works, Inc., Auburn, N. Y., a

corporation of New York Original application June 16, 1943, Serial No.

491,078. Divided and this application February 18, 1944, Serial No. 522,976

5 Claims.-

This invention appertains to apparatus for applying plastic coatings to flexible strips, webs,

tapes, and other similararticles and shapes, and

this. application is a division of my copending apphcatlon Serial No. 491,078, filed June 16, 1943.

In machines heretofore employed in applyingplastic coatings to articles of the aforementioned character, considerable dimculty has been met in obtaining a firm adhesion between the plastic coating and the base material onto which'it is ear and in addition, it has been practically impossible to apply a coating of uniform thickness, particularly Where the coating completely surrounds the base material. These problems are of considerable lniportancein the application of ecor tive and/or protective coatings to articles of wearing apparel, such as belts, braces (sus- Fenders), bands, and the like, which are of reater transverse width than thickness, and also iish lines, with the result that the plastic coatmg is not equally distributed about the article by reason of the lack oi pressure balance on the Elastic as it names through the usual extrusion Still another serious problem presented by the conventional plastic coating machines is t tendency of the plastic material to deteriorate or decompose by backing or piling up in bends or turns through which the plastic is directed through the extrusion machine and die, with the quent formation of "dead spots. This Problem is especially troublesome in those ma chines which are characterized by a cross-feed, that is, where the plastic makes substantially a 90 turn in the extrusion machine itself, or where the plastic is fed onto an article which is moving transversely to the direction of flow of the Plastic. Some of the plastics, particularly vinyl chloride, decompose rather rapidly if allowed to stand or pile up in the coating machine or die, even for a few minutes, and when decomposition has taken place, the plastic becomes dark in color or streaked; with consequent darkening or streakof any fresh plastic which may be passing through the machine adjacent to the decomposed dead spots. Obviously. this produces a very inferior and unsightly coating, wholly unfit for decorative purposes in the ca e of articles of wearing apparel.

with the-foreg ing principal difliculties in V among many others not specifically mentioned, I fl e provided a new and improved apparatus which serves to preliminarily remove moistu and air from the interstices and indentations of the article orbase material to be coated with plastiqas obtained by preheating the base material; followed by the application of vacuum to 'the'material before the plastic coating is applied thereto. The preheating and vacuum applying means, together with a' progressively increasin application of pressure onto the plastic coating after the coating is applied to. the base material, as obtained by a tapered finishing die, insure the positive forcing of the plastic into the base material, in the case of woven fabric, and in any case, there results a firm adhesion between the base material and the plastic, all without the production of air bubbles or air pockets which are so commonly present in such plastic coated articles.

Another object of my invention is the provision of an improved means for producing a "streamlined flow of plastic onto the basematerial to be coated, and for balancing the pressure throughout the plastic stream just before it is applied onto the base material, thereby permitting an exceedingly close regulation of the flow of plastic, with consequent application of the plastic in uniform thickness about all sides of the base material. With regard to the "streamlining of the plastic how, this also serves the advantage of reducing resistance to flow and substantial elimination of dead spots and consequent decomposition of the plastic. l

A further object of my invention is to facilitate the feed of normally fiat strips, webs, belts and the like, of flexible material, by the provision of means for initially curling the material transversely, preferably after the removal of moisture and air therefrom as previously mentioned, to enable the same to.be passed into an extrusion die without substantial interference with the flow of the plastic through the die. By curling the base material, wider strips or webs can be successfully accommodated than would otherwise be possible with an extrusion die of given dimensions, and without weakening the die or other forming head.

Ancillary to the aforementioned object, my invention additionally contemplates-the provision of-an ironing or forming die which flattens and smooths out the initially curled strip material and thereafter guides it in a straight path which is substantially parallel with the flow of the plastic coating material which is to be ultimately applied thereto.

A still further object of my invention is to p vide an extrusion die or forming head which is so constructed as to produce a substantially selfcleaning action upon the base material to be pended claims.

2-: of Figure coated should any plastic back up into the guides.

and also so constructed as to minimize the backing up of the plastic material.

Other and further objects'and advantage of the invention will be hereinafter described, and the novel features thereof defined by the ap- In the accompanying drawings:

Figure 1 me view in vertical section through an extrusion die or forming head constructed according to my invention, the same being shown as a plied to a conventional plastic extrusion ma-. chine of the cylinder and feed-screw type, as emspaced relation to said central 4 axis. ncartheouter margin of the spider. The end ofthespider next to the feed-screw 3 is centrally bored and threaded, as at I 2, to receive a correspondingly threaded end on a tapered point I! which projects into the belled bore or-chamber 1, as will be best understood from reference to Figure 1 of the drawings.

- This tapered point It serves to divide the plastic played in applying plastic coatings to flexible and the finishing die, with their associated heat- I ing chambers; I

Figure 4 is'a horizontal sectional view taken on the line 4-4 of Figure 2;

Figure 5 is a sectional view taken on the line 5-5 of Figure 1, to illustrate the uncurling of the initially curled strip material as it enters the ironing and guiding die;

Figure 6 is a sectional view taken on the line 8-6 of Figures 1 and 4 respectively, near the forward end of the ironing die;

re 7 is a sectional view taken on the line 7-7 of Figure 1, showing the strip curling guide which initially imparts a transverse curl to the strip material before it passes into the extrusion die or forming head: and

Figure 8 is a perspective detail view of the 40 opposite end is threaded as at I9.

passing axially through the chamber I, andto streamline the plastic as it approaches the spider Io where it enters into the spaced p ssa es II in the latter. The webs II between the es I I are preferably bevelled or tapered towards each passage at the plastic entering end of the latter, to aid in smoothly directing the plastic into the passages through the spider.

Positioned forwardly of the spider II in the bore a is a combined ironing and guiding die n which is made up of an outer shell or bell-piece I5, preferably cored out at I6 to provide a steam chamber, and an inner split die II inwardly spaced from the outer bell I! to form an annular plastic passage I8. The split die I! is preferably pinned together and sc'rewed' into the end of the spider I0 opposite to the tapered point I which As will be understood from reference 1 to 4 inclusive, the annular space I. formed between the outer shell or bell-piece II and the inner die orguide Il receives the plastic material as it passes through the as H in the backstop shoe or plug which cooperates with the ironing or guiding ,die in reopening and entering the strip material into the ironing die, and otherwise prevents the plastic from backing up into the strip entering end of the forming head.

Lil e reference characters designate correg parts In the severalngures oi the drawings, where i designates, in fragmentary form, the discharge end of a conventional extrusion tion. & illustrated in Figure 1 of the drawings. said extrusionmachine includes the usual plastic machine which may be of any suitable construcfeeding cylinder 2 through which the plastic is.

ied axially by the usual screw 3. The discharge end of the cylinder 2 is preferably threaded at 4 to receive a correspondingly threaded end 5 of a tubular hell 6 forming part of an extrusion die or forming head.

as will be best seen from Fi ure l of the draw 1 13s. the end of the shell 8 which is threadedly connected to the cylinder 2 is longitually bored t provide a belied or tapered chamber 8 through which the plastic material enters the extrusion die or iorming head from the feed-screw '3. At

the forward end oi. the tapered chamber F, t

tubular shell I is provided with an interior shoulder I, beyond which the shell is bored cylindrically to a continuously uniform size to the extreme for- Ward and of the shell, a indicated at Q.

Mounted in the bore s and abutting against the shoulder 8 is a spider II! which is provided with a plurality of as II extending axially lif-"f: the spider, said gee being spaced eqllidistantly from each other about the central axis of the spider. and being located in outward I spider ll, and continues the streamlining of the plastic. flow. Due to the tapering of the plastic,

passages and chambers, the cross section of the plastic stream progressively reduces asthe plastic advances towards the forward end of the forming head. In this connection, the shaping of the outer-bell I5 and the inner die or guide II is;

quite important from the standpoint of the streamlining effect upon the plastic material, and also from the standpoint of balancing the pressure of the plastic throughout the plastic stream. To the latter end, the forward end of the annular passage l8 takes the form of a straight-away, as at 20, to allow the pressure to become equal all around the plastic stream before it leaves passage.

At the forward end of the combined ironin die and guide is, there'is mounted in the bore 0 of thetuhularshellflafinishingdie 2i havinsanaxial passage 22 extending therethrough. The rearward end of this ge 22 is belied out to form an annular shoulder, as at 23, which lies directly forwardly of the discharge end of the straight-away passage 20 in the combined ironins and guiding die i4. Thus, this shoulder contributes to the balancing of the plastic prese to, by preventsage- 22 in the finishing die 2!. in other words, the go 20 is spaced outwardly somewhat beyond the center of the passage 22 inthe die, and by virtue of the provision oi the shoulder 28 which is disposed forwardly of the passage 2|,

the flow of the plastic material is held back a slightly in the straight-away passage it unti the pressure on the plastic has had an 01 9 tunity to become perfectly balanced about the entire plastic stream. Thereafter, the plastic pass from the boiled end 23 of the pc 22, into a portion of the passage 22 which has a lon ner, as indicated at II. Beyond the tapered portion 2, the e: 22 is uniform, as indicated at 25. The purpose of this construction of toiligures the passage 22 just described will u more fully appear.

Surrounding the finishing die 2| is a collar 28 which is preferably milled out or cored out at 21 and closed at its forward end by a sealingring 28 to form a steam chamber. An end plate 28, likewise preferably cored out as at 30 to provide an additional steam chamber, abuts against the outer end of the collar 28 which is provided at its rearward end with a shoulder 3| abutting against a corresponding shoulder 32 on the finishing die 2!. Bolts 33, passing through the end plate 29 and'threadedly received in the outer end of the tubular shell 6, serve to clamp the end plate 29 snugly against the collar 26 and finishing die 2|, this clamping action also serving to firmly secure the ironing dieand guide l4 and the spider ID in their assembled relation as previously described. Keys 33' and 33" may be provided to maintain accurate registry of the die parts when assembled, as shown in Figure 4. In order to more effectively heat the extrusion die or forming head, should additional heat other than is afiorded by the steam chambers I6, 21 and 30 respectively, be required, the tubular shell 5 may be provided with an outer collar or stem jacket 34, which is suitably cored out to provide additional steam chambers 35 having communication with the steam lines 38. To facilitate the application of the steam jacket 86 onto the tubular shell 6, the forward end of the shell is preferably threaded, as at 3'9, for cooperation with the internally threaded bore of the steam jacket, thus permitting the steam jacket to be readily removed at will.

Having described the general features of the extrusion die or forming head,,wlth particular regard for the flow of plastic therethrough, there remains to be described the feed 0! the article or base material to be coated with the plastic. As will be best seen from reference to Figure l of the drawings, the article or base material comprises, for the purposes of this illustration, a flexible strip or web of woven fabric, but it is to be understood that my invention is not limited thereto. Likewise, while the strip has been shown in a form which is rectangular in outline and considerably wider than it is thick, I do not intend to be limited to the particular dimensions or shape illustrated in the drawings, since other articles of other sizes and shapes may be similarly coated with plastic by suitable changes in the proportions and shapes of the parts of the extrusion die or forming head.

With the foregoing brief introduction as to the character of the material or article to be coated with plastic, it will be understood that the flexible strip material, designated 38, is fed from a suitable source, not shown, and preferably passes between opposed banks of infra-red ray lamps, diagrammatically illustrated at 39, 38, by means of which the strip is preheated and thoroughly dried out to remove any moisture which may be Present therein. After this preheating and moisture-removing operation, the strip passes into a vac um tube M, which may have a tight fitting asket M, or other sealing means, closely conforming to the shape of the strip, at the upper end of the tube. At intervals along the tube All, a manifold 42 is connected thereto, and the manifold is in turn connectedto a vacuum pump (not shown) by means of which an effective vacuum will be drawn to remove any air which is present in the indentations or interstices of the strip 38. By reason or the connection of the disposed respectively above and below the form 45 to prevent air from being drawn into the vacu-' manifold 42 to the tube ll at intervals along the length oi. the latter, a relatively high vacuum willbe obtained by the time the strip reaches the inner end of the. tube, even though some air may enter past the gasket or seal II at the outer end of the tube; The inner end of the tube 40 fits into the upper end of a nipple 43, which may be firmly clamped thereto by the clamping bolts 44, best seen in Figure 2.

Disposed in the upper end of the nipple 43 at the bottom of the vacuum tube I is a form or curling die 45 through which the strip 3! passes, and by means 01 which the strip is curled from a normally flat form into a generally V-shaped or tubular form. as best shown in Figure '7. Suitable Saskets or other seals (not shown) may be um tube at the Joint between the vacuum tube and the nipple ll.

The lower end of the nipple I3 is threadedly received in an opening ll provided therefor in the wall of the tubular shell 6. From the nipple 43 projects downwardly a hollow bolt 41 concentrio with the axis 0! the nipple, said hollow bolt fitting in a, bore through the wall or the tubular shell 6, extending at an angle of approximately 32 from the vertical. coextensive with the bore through the hollow bolt 51, and forming a continuation thereof, is another bore 48 formed in the solid web of the spider it! between an adjacent pair of plastic passages ll. Thus, the flexible strip 38, after passing through the form or die 35, continues in its transversely curled or tubular form through the hollow bolt M and the bore it, beyond which it comes into engagement with the rearward end of the split ironing die or uide ll. This end of the ironing die or guide W is so shaped as to cause the curled strip it to be opened up and fed in a restored fiat condition through a passage til corresponding in shape to the normally flat shape of the strip and extending longitudinally through the die W. The restoration of the flat shape of th strip to is aided by the use of a special backstop shoe or plug to. having a pin 5i projecting from its rearward side into a correspondin opening 52 formed in the tapered point it. The forward end of the shoe. at its lower side, closely fits the rear end of the lower half or the split die IT, as indicated at 53, whereasthe upper portion of the shoe is sp ced from the rear end of the upper-portion of the sp it die as indicated at 55, to permit the strip 38 to pass therebetween and enter the passage 48 through the die ll. As the strip then moves through the passage 45, it is ironed or smooth out perfectly flat by the die i1 until it emerges balancing of the pressure of the plastic before it v is applied onto'the strip; as previously explained.

the uniformity of application of the plastic coating is closely regulated and accurately maintained. i

Now as thestrip with the plastic coating thereon advances through the finishing die 2!, the tapering or the e along the part designated .24 causes the plastic to penetrate the strip, in the 7 case or wovenfabrlc, or otherwise fill inirresularities or indentations in the strip andproduoe a firm bond between the plastic coating and the strip material. Beyond the tapered portion of; I the 22, the coated strip continues through herein shown and described, my invention is not a straight-away portion 25 which completes the smoothing and shaping of the coating to the de sired uniform thickness, leaving the strip uniformly coated with the plastic which is firmly bonded thereto without any air bubbles or air pockets in the coating, or between the coating and the strip.

After the coated strip leaves the end of the die or forming head, it may be passed through a water-coolingtrough (not shown). It will be understood that the feed of the strip is obtained in any suitable manner, as by exerting a pull thereon from the forward side of the extrusion die or forming head with the aid of a pulley which 1 is preferably driven by a variable speed motor.

By careful temperature control of the sections of the die or forming head, and by synchronizing the speed of the plastic machine and the speed of the strip to be covered, the desired plastic coatmg application can be perfectly regulated. It;

may also be mentioned in this connection that, if desired, the heat applied to the finishing die by the steam chamber 21 may be in the nature of a superheat to aid in the production of a firm bond between the plastic and the strip to be coated as the strip passes through the tapered portion of the finishing die. By reason of the preheating of the strip by means of the infra-red ray lamps 39, the parts of the extrusion die or forming head are not chilled by the subsequent contact of the strip therewith. This also contributes to the improved quality of the finished product. It will be understood from the foregoing that by removal of the end plate 29, after removal of the clamping bolts 33, thespider I0, ironing and guiding die It, and the finishing die 2! mayallbe removed from the tubular shell 6 for the purposes of cleanin the same when the occasion so re-- quires. or to permit the substitution of other dies of suitable size and shape to conform to the difierentsiaesandshapesofarticlestobecoated with plastic. non die or forming head as a unit from the cylinder! ofthe. machineesbyunscrewing the head therefrom, convenient acce'mis given to thepcint i3topermitth'elatterwthere-' afterbeandremovedfromthebelled ortachamberi. Thisremovalofthetapointl3,alongwiththeshoeor phisfl.aifordscmvenientaccesstotheinterlor oftheheadforth a-a e; ofpermittingthestripfltobe theguidesanddiepartsinadvanceof the 1... ofentranceofthe strip into thesplit dieorguideii.

Byotthecloseregulaticnor oftheandflowofplasdcattheap- 'uroaehtcthefdieitis .ingjotthefinalooatingwhiehha heretaforebeen soevident inplasticarticlesof'thischaraster. It is to be of that whil duties ofthevinri chloridetype Also, by disconnecting the extra eflectively used with my invention, various other,

plastics may be-employed in lieu thereof with l y good results. Likewise, while the specific details have been confined theretoas changes and alterations may be made without departing from the spirit thereof as defined by the appended claims.

Iclaim: 1. .An extrusion head adapted to be attache to an extrusion machine for continuously extruding a plastic material around a moving flexible base in a path parallel to the path of travel of the plastic material through the head, said extrusion head having a plastic-receiving opening at one end and an extrusion die at the other end opposite to the plastic-receiving opening, a spider located in said head between the plastic-receiving'opening and the extrusion die, said spider being provided with a plurality of plastic-conveying passages extending therethrough and ar ranged in equidistantly spaced relation to each other about the axis of the path of travel of the plastic material through the head, said spider also having a lateral passage formed between two adjacent plastic-conveying passages, means for directing the flexible base to be coated into the extrusion head and through the lateral passage in the spider in a path generally normal to the path of travel of the plastic material through the head, a guide die disposed between the spider and the extrusion die for guiding the flexible base through the head'to the extrusion die in a path substantially parallel to the path of travel of the plastic material through the head, and a backstop shoe at the entrance of the guide die and cooperating with the latter to direct the flexible tion to a point adjacent to the outlet end of the guide die and terminating in a straight-away passage leading to the extrusion die, and the extrusion die is provided with a belied mouth into which the guide die projects, and forming a beveled shoulder in the path of the plastic at the -mouth of the extrusion die to partially obstruct the plastic flow at the end of the straight-away aforesaid whereby to uniformly balance the plastic pressure vat all points about the flex iblebaseastheplasticisappliedtothebaseat' the end or the guide die.

a. An extruding die or forming head for apply-- in plastic m an :1: t0 flexible strips and the like, comprising a tubular-shell or body adapted tobesecuredtotheplasticfeedcylmderofa extruding machine, said shell having an a; tapered plastic chamber in the plastic receivingendthereofandauniformaxialbore provided in its opposite end and forminga continuation of the tapered chamber aforesaid, a spider removably mounted in said axial bore next to said tapered plastic chamber, said spider having a plurality of spaced plastic es extending therethrough which serve to direct the plasticcedfromthetaperedchamberinthe maybe I! rormorapiuraliwofspacedstreamameansior directing and advancing the flexible strip to be coated laterally through the spider between the spaced plastic streams, and thence axially through the tubular shell along the central axis of i the bore therethrough, said means including a strip guide disposed exteriorlyrot the path of the.

plastic stream and serving to transversely curl the strip preliminary to advancement of the strip laterally through the spider between the spaced plastic passages therein, a bell and interiorly spaced die mounted in the boreof said tubular shell contiguously to said spider, said bell and spaced die defining therebetween a substantially uninterrupted, generally annular plastic passage of progressively diminishing cram section and terminating in a straight-away passage of uniform cross section at the forward end of the bell, said interiorly spaced die having a strip guiding passage therethrou'gh conforming closely to the dimensions 'of the strip to smooth or iron the 5. In apparatus for applying plastic coatings .to flexible strips and the like, the combination with a cylinder having a feed screw for feeding a plastic material therethrough, of an extruding die adapted to be connected to the discharge end or said cylinder, said extruding die comprising a tubular shell having a plastic receiving chamber at one'end thereof, a spider disposed in said shell oi the strip through an opening in the shell in latter, and having means at theentrance of said guiding passage for opening the curled strip and directing the same into the ironing die passage in a refiattened condition, said ironing die terminating at the forward end of the bell in proximity to the endof the straight-away annular passage aforesaid so that the plastic will be dealinement with the lateral bore in the'spider', means for transversely curling the strip into substantially tubular form preliminary to advancement of the strip laterally through the spider,

means for directing the strip and the plastic in generally parallel axial paths through the shell beyond the spider aforesaid while balancing the plasiic pressure substantially uniformly about thestrip preliminary to deposit of the plastic upon the strip in the form of a coating at a point beposited upon and about the strip in-the form of:

' a coating at the forward end of the bell and ironing die, and a finishing die disposed forwardly of the bell and ironing die aforesaid and serving to smooth and shape the plastic coating on the strip to thedesired shape and thickness;

yond the spider, mean ior reopening and flattening the strip preliminary to the application of the plastic coating onto the same, and means for compressing the plastic coating onto the strip and for finally smoothing and shaping the plastic coating to thedesired shape and thickness.

HERBERT ill-TON COOK, JR. 

